The siblings could run
tailscale ping nodeIP/nodeName
This not only shows if they are connected via a DERP (relay) but also retries to connect them directly a few times.
If that doesn’t work out it can sadly be quite hard figuring out why a DERP is used instead of a direct connection.

There is a project that can run some backgrounds, but is very experimental and IMHO not suited for running constantly as a desktop background. WPE is way too deep in specific windows features to be able to run on linux smoothly.

I am with you on this one. I do think it would be appropriate to have a disclaimer in the beginning, saying that these words used to have a different meaning, and that in the context of the time they were written they meant different things than today.
There is a German book where this is done that uses the N word for people of color.
This is the more appropriate way of handling this, because i am totally with you: we shouldn’t change what was written in books. If we start doing that, we destroy what authors have done, and in a sense we also edit history, because in this case we try to erase that these words were used in another context back in the days.